JPH02214521A - Controller for injection amount of gaseous ammonia - Google Patents

Abstract

PURPOSE:To inject an appropriate amt. of gaseous ammonia by providing an integral controller for inputting a deviation signal from a comparator for inputting an excess gaseous ammonia concn. set value signal and an ammonia concn. signal and for outputting a conversion rate correction signal to be inputted to a computing element. CONSTITUTION:The computing element 6 for correcting the reactant gaseous ammonia amt. signal 1 by a set value signal 120 for the sulfur content in fuel is provided, an ammonia injection amt. signal 20 is outputted. An excess gaseous ammonia concn. set value 3 outputted from a gaseous ammonia concn. setter 113 and a gaseous ammonia concn. signal 2 outputted from a gaseous ammonia densitometer 111 are inputted to the comparator 115. A deviation signal 4 outputted from the comparator 115 is inputted to a high/low signal detector 5, and the deviation signal beyond the upper or lower set value is selected. The signal outputted from the selector 5 is inputted to the integral controller 7, the conversion rate correction signal 8 proportional to the time when the deviation signal 4 is beyond the upper or lower set value is outputted, and the signal 8 is inputted to the computing element 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for controlling the amount of ammonia gas injected for desulfurization of an electrostatic precipitator (hereinafter referred to as EP) used in a boiler.

[Conventional technology]

In a device that performs desulfurization by injecting ammonia gas into the inlet flue of an IP, desulfurization is performed by injecting ammonia gas into the inlet flue 107 of the EP 108 through an injection pipe, as shown in Figure 2. The purified gas is discharged through a flue 109 on the EP outlet side.

The conventional control device for controlling the amount of ammonia gas injected is disclosed in Application Publication No. 171733 of 1988 (Showa 6).
There is a method shown in FIGS. 2 and 3, which was proposed by U.S. Pat.

That is, EP108C) The amount of ammonia gas injected into the inlet flue 107 is determined by the fuel flow rate signal 101, the sulfur content set value signal 120. EP output ammonia concentration setting device 11
3 and the output signal of the ammonia gas concentration meter 111 that detects the ammonia gas concentration in the exhaust gas at the outlet flue 109 of the EP 108 are input, and the output signal of the 9 arithmetic circuit 102 and the ammonia gas injection pipe 106J'C are installed. The output signal of the ammonia gas injection amount detector 103 and the regulator 1
04, and the control valve 105 installed in the cyanmonia gas injection pipe 106 is opened and closed according to the deviation signal to increase or decrease the amount.

In the arithmetic circuit 102, the amount of ammonia gas for reaction is determined by a reaction ammonia gas amount calculation circuit 112VC which receives the fuel flow rate signal 101, and the amount of ammonia gas for reaction is input to a correction circuit and is determined by the sulfur content in the fuel. The corrected reaction ammonia gas amount is determined. Further, the fuel flow rate signal 101 is input to the surplus ammonia gas amount calculation circuit 114 to determine the surplus ammonia gas amount, and the surplus ammonia gas amount outputs the set value of the surplus ammonia gas concentration remaining at the outlet of the EP 108. A correction circuit inputs a signal from the surplus ammonia gas concentration setting device 113, and the corrected surplus ammonia gas amount is determined. The above corrected surplus ammonia gas amount is added to the above corrected reaction ammonia gas amount by the surplus ammonia gas adder 117, and the surplus ammonia gas concentration setting device 113 outputs a nine set value. Based on the actual measurement value outputted by the ammonia gas concentration meter 111, the sample control circuit 116 performs correction based on the surplus ammonia gas amount correction signal outputted by the comparator 115, and the ammonia gas injection amount 110 is output.

The above ammonia gas for graystone undergoes a reaction with the sulfur content contained in the fuel as shown in the following reaction formula, and is produced by ammonium sulfate (N
Ammonium sulfate (NH4) SO, is removed by EP 108.

S+0. →Sow 280 elephants +0! →2SOs SOs+HxO→H,5o4 N Hs 10He SO4→NH4H3O4NHaH
8Oa+NHs→(NH4)*SOa The above reaction ammonia gas amount is calculated in the calculation circuit 102 based on the above reaction formula.

The reason for determining the amount is that if there is a shortage of ammonia gas, the reaction of the following formula will proceed to the right (NH4)*SO42NHs + N H4H804 and produce acidic ammonium sulfate NHaH8O4, which will have a negative impact on EP. be.

[Problem to be solved by the invention]

In conventional devices, the response speed of the ammonia gas concentration needle is slow (approximately 10 to 40 minutes), making it impossible to inject an appropriate amount of ammonia gas using normal proportional-integral-derivative control.

First, the concentration of Son contained in boiler exhaust gas generated by combustion of sulfur content changes partly due to a gradual increase over time (approximately 100 cm increase per year) and partly due to boiler operating conditions, excess air ratio, temperature, etc. There are parts that change rapidly, and conventional equipment cannot adequately respond to these changes.

The reason for the gradual increase in the Son concentration is that heavy metals accumulated in the boiler increase as the boiler is used, and this acts as a catalyst to convert SO1 to SO1.

The present invention solves the above problems, always injects an appropriate amount of ammonia gas, minimizes the amount of surplus ammonia gas,
The aim is to provide a device that can reduce running costs.

(Means for Solving Problem a) The control device of the present invention is a control device that outputs an ammonia injection amount signal and includes a computing unit that corrects a reaction ammonia gas amount signal using a sulfur content set value signal in the fuel. A comparator that inputs the surplus ammonia gas concentration setting value signal output from the ammonia gas concentration setting device and the ammonia gas concentration signal output from the ammonia gas concentration meter, and inputs the deviation signal output from the comparator to set the upper and lower limit set values. A high/low signal selector selects the exceeded deviation signal, inputs the signal output by the same high/low signal selector, outputs a conversion rate correction signal proportional to the time when the deviation signal exceeds the upper and lower limit set values, and outputs the same signal. The present invention is characterized in that it includes an integral regulator that inputs input to the arithmetic unit.

[Effect]

In the above, the comparator inputs the surplus ammonia gas concentration setting value signal from the ammonia gas concentration setting device and inputs the cyanmonia gas concentration signal from the ammonia gas concentration meter,
Outputs deviation signal.

The high/low signal selector inputting the same deviation signal selects the deviation signal exceeding the upper limit or lower limit set value and outputs the signal to the integral controller. The integral regulator inputs the above signal and outputs a conversion rate correction signal proportional to the time when the deviation signal exceeds the upper limit or lower limit set value, and the conversion rate correction signal is input to the arithmetic unit. The control device outputs an appropriate ammonia gas injection amount signal by correcting the conversion rate correction signal.

According to the above, in addition to the control that corresponds to normal S Os concentration changes that change relatively quickly, the conversion rate of Sow to Pros can be gradually increased over time by inputting a conversion rate correction signal to the calculator. As a result, a control device that can inject ammonia gas while minimizing the amount of surplus ammonia gas has been realized.

〔Example〕

An embodiment of the present invention is shown in FIG.

In this embodiment, the parts other than the part where the signal is fed back from the comparator are the same as the conventional device, so the explanation will be omitted.

In this embodiment shown in FIG. 1, an ammonia gas concentration setting device 1
A comparator 115 which inputs the surplus ammonia gas concentration setting value signal 3 outputted by 13 and the 9 ammonia gas concentration signal 2 outputted by the ammonia gas concentration meter 111, and outputs a deviation signal 4.
, an integral regulator 7 which inputs the deviation signal 4 through a high/low signal selector 5 and outputs a conversion rate correction signal 8, and a reaction ammonia gas amount calculation circuit 112 outputs a reaction ammonia gas amount signal l. A calculator 6 inputs the fuel sulfur content set value signal 120 and the conversion rate correction signal 8 and outputs a corrected reaction ammonia gas amount signal 9, and a surplus ammonia gas amount calculation circuit 114. A computing unit 11 which inputs the outputted surplus ammonia gas amount signal 10 and outputs a surplus ammonia gas amount signal 15 corrected by the surplus ammonia gas concentration setting value signal 3; An adder/subtractor 12 that inputs and adds the signal 9 and the surplus ammonia gas amount signal 15 and outputs the ammonia amount signal 13, and a correction ammonia gas amount signal 17 outputted by the proportional integral regulator 16 that inputs the deviation signal 4. and an adder/subtractor 14 that inputs the ammonia amount signal 13 and the surplus ammonia gas amount signal 19 for correction and outputs an ammonia injection amount signal. There is.

In the above, the deviation signal 4 between the surplus ammonia gas set value signal 3 outputted from the comparator 115 and the ammonia gas concentration meter signal 2 is input to the high/low signal selection 1 and the device 5. The same high/low signal selector 5 outputs a signal to the integral regulator 7 when the deviation signal 4 exceeds the upper limit or the lower limit set in the selector 5, and the regulator 7 outputs the signal to the above upper limit or lower limit. When the lower limit value is exceeded, a conversion rate correction signal 8 proportional to the running time is output. The conversion rate correction signal 8 is input to the calculator 6 which has input the reaction ammonia gas amount signal 1 and the sulfur content setting value signal 120.
The calculator 6 outputs a corrected reaction ammonia gas amount signal 9.
Output.

In the high/low signal selector 5, when the deviation signal exceeds the upper limit value or the lower limit value, the signal is sent to the integral controller 7, and the regulator 7 sends the signal to the integral controller 7 for the time when the deviation signal exceeds the upper limit value or the lower limit value. Since the conversion rate correction signal 8 is outputted in proportion to be exposed.

The corrected reaction ammonia gas amount signal 1a outputted from the arithmetic unit 6 is outputted by the surplus ammonia gas amount calculation circuit 114 and corrected by the arithmetic unit 11. The adder/subtracter 12 outputs an ammonia amount signal 13 and inputs it to the adder/subtracter 14.

Further, the deviation signal 4 outputted by the comparator 115 is input to the proportional-integral regulator 16, and the regulator 16 outputs a correction ammonia gas amount signal 17 corresponding to the change in the concentration of S Os, which usually changes relatively quickly. do. The correction ammonia gas amount signal 17 is input to the height setting device 18. The height/low setting device 18 generates a surplus ammonia gas amount signal for correction, which is obtained by adding a limit to the ammonia gas amount signal 17 for correction, in order to prevent excessive or insufficient amount of ammonia injection due to the response delay of the ammonia concentration meter 111. Outputs 19.

The surplus ammonia gas amount signal 19 for correction is input to the adder/subtractor 14, and the adder/subtractor 14 receives the ammonia amount signal 1 based on the surplus ammonia gas amount signal 19 for correction.
3 is corrected, and an ammonia injection amount signal 20 is output.

In addition to the above, it has become possible to perform control over the gradual increase in the conversion rate from SOl to SOs over time, and mental control in response to changes in the concentration of normal SOs, which change relatively quickly. ``We have achieved a control device that can inject ammonia gas while minimizing the amount of ammonia gas.

〔Effect of the invention〕

The present invention provides a control device that outputs an ammonia injection amount signal and is equipped with an arithmetic unit in which a reaction ammonia gas amount signal is corrected by a sulfur content setting value signal, and a comparison device that inputs an excess ammonia gas concentration setting value signal and an ammonia concentration signal. By providing an integral regulator that inputs a deviation signal from the converter via a high/low signal selector and outputs a conversion rate correction signal that is input to the above-mentioned arithmetic unit, the normal SO
In addition to the control corresponding to concentration changes, by inputting a conversion rate correction signal to a calculator, SOl can be improved over time.
Since it has become possible to control the gradual increase in the conversion rate to s, a control device that can inject ammonia gas while minimizing the amount of surplus ammonia gas has been realized.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of an ammonia gas injection desulfurization apparatus, and FIG. 3 is an explanatory diagram of a conventional apparatus. DESCRIPTION OF SYMBOLS 1... Reaction ammonia gas amount signal, 2... Ammonia gas concentration signal, 3... Excess ammonia gas concentration setting value signal, 4... Deviation signal, 5... High/low signal selector, 6... ... Arithmetic unit, 7... Integral controller, 8... Conversion rate correction signal, 9...-Ammonia gas amount signal for reaction, 1
0... Surplus ammonia gas amount signal, 11... Arithmetic unit, 12... Addition/subtraction device, 13... Ammonia amount signal, 14... Addition/subtraction device, 15... Surplus ammonia gas amount signal , 16... Proportional integral adjuster, 17... Ammonia gas amount signal for correction, 18... Height setting device, 19
... Surplus ammonia gas amount signal for correction, 20... Ammonia gas injection amount signal, 101... Fuel flow rate signal,
111...Ammonia gas concentration meter, 112...Ammonia gas amount signal for reaction, 113...Ammonia gas concentration setting! , 114... Surplus ammonia gas amount calculation circuit, 115... Comparator. Agent Patent Attorney Akatsuki Sakama 2 people 1 color fi 2m shoulder 3rA

Claims (1)

[Claims] In a control device that outputs an ammonia injection amount signal and is equipped with a calculation unit that corrects a reaction ammonia gas amount signal based on a sulfur content set value signal in the fuel, the surplus ammonia gas concentration set value signal outputted by the ammonia gas concentration setting device. A comparator that inputs the ammonia gas concentration signal output by the ammonia gas concentration meter, a high/low signal selector that inputs the deviation signal output from the comparator and selects the deviation signal that exceeds the upper or lower limit set value, and the same high/low signal. It is characterized by comprising an integral controller which inputs the signal output from the selector, outputs a conversion rate correction signal proportional to the time when the deviation signal exceeds the upper limit or lower limit set value, and inputs the signal to the arithmetic unit. A control device for the amount of ammonia gas injected.